Chem Exam 1 Flashcards
Signs of a chemical change
Color change
Combustion
Atoms rearranging
Physical properties?
Can be observed without changing composition of matter Color Odor Density Melting pt. Boiling pt. hardness
Extensive properties
Mass
Volume
Chemical properties?
Properties which become evident during a chemical reaction
Flammability
Intensive properties
Melting pt.
Density
Temp.
Pure substance
Something that has a constant composition
Cannot be separated into other kinds of matter by PHYSICAL processes
Elements
Cannot be chemically decomposed into simpler substances
Compound
Can be broken down into elements by chemical processes
2 or more elements chemically combined
Mixture
Combination of at least 2 substances that can be separated by physical methods into different substances
Homogenous mixture
Uniform in macroscopic level, no amount of magnification can reveal components, constant properties
Kelvin conversion
+273.15
Dalton’s Atomic Theory
- All matter is composed of solid, indivisible particles called atoms. (NT)
- Atoms of a particular element are identical.(T)
- Atoms of one element differ from atoms of another. (T)
- Atoms of different elements combine in numerical proportions to form compounds.
- In chem. reaction, matter is neither created or destroyed, or changed into atoms of another element.
Cathode Ray Tube Experiment
- Sir JJ Thomson (Plum Pudding Model)
- had positively charged platform cathode
- Deduced nucleus was positively charged because most particles passed through foil without deflection.
- Most alpha particles were not deflected or slightly deflected. Others largely deflected.
- Proposed: Most of mass with electrons occupying space
- Learned particles are fundamental constituents of matter
- PARTICLES WERE NEGATIVELY CHARGED
Charge/Mass Ratio
JJ Thomson determined the angle at which the particles deflected
atomic weight
mass of one atom of an element (mass spectrometer)
Rutherford
Concluded:
-Most of volume is empty space which contains electrons
-Atom contains positively charged nucleus
-Mass of atom is concen. in nucleus (pos. charge)
-Positive charge is due to protons
No. electrons= no. protons
-Electrons and nucleus are held together by forces of attraction
Ionic compound
- Solid
- Have different properties than constituent elements
- Dissolving an ionic cmpd. in water produced ions in solution
Combination Reaction
2+ reactants combine to form one product
Decomposition Reaction
When one reactant is decomposed to give 2 or more products (opposite of combination reactions)
Theoretical Yield
Maximum amount of product that can be obtained (determined by limiting reactant)
Solvent
Dissolves the solute
Substance present in greatest quantity
Solute
Dissolves in solvent
Electrolyte
Substance in aqueous solutions containing ions
Nonelectrolyte
Doesn’t form ions in solution (most molecular compounds)
chemical equilibrium
When relative numbers of each type of ion/ molecule in reaction are constant over time
Neutralization reaction
When a solution of acid and a solution of base are mixed, the products have no properties of original A/B
Strong Electrolyte
(Strong acids and strong bases) Produces many ions when it dissolves in solution
Weak Electrolytes
(Weak acids and weak bases) Partially dissociate and react with water to form ions in solution
Acid
H+ donor, releases H+ ions when dissociates in water
Base
H+ acceptor, produces OH-ions when dissolved in solution
Deposition
When gas transforms to solid
Solution
A homogenous, molecular mixture of two or more substances
Substance
A form of matter with constant chemical composition and characteristic properties. Cannot be separated physically without breaking chemical bonds
